When to start H&G roots excellerator?

I'm at 7 days from seeds sprouting. I called H&G and the guy said for sure. He said he soaks his plugs in it prior to sowing. Is this legit? I always thought it wasent a good idea to feed any nutes for 2-3 weeks.
I want to start useing it but am nervous.

Also would the same go for mycos? Starting now. It's specifically myco madness by humboldt nutrients.
Thanks!

I use HG roots excel for my fresh cut clones ,its kelp based it provides trace elements so your good use it ,I'm using 5ml per gal a little more then it recommends and I see no problems roots in 7 days. This is the perfect time to introduce beneficial microbes especially during transplant so use the myco madness! Im a true believer of microbes I use Recharge its the same thing but some added benefits .Use both products NOW your plants will thanks you I promise,also once they establish get a enzyme product and molases to help those microbes with the work!!!

I also use roots excel from day one

From day one along with drip clean and your mycos. You can deff soak your plugs with it

when you decide you have too much money and dont want it anymore